package com.example.demo.utils;


import javax.servlet.http.HttpServletRequest;

/**
 * 客户端真实IP
 **/
public class RequestIpUtils {

    private static final String UNKNOWN = "unknown";

    private static final String SEP = ",";

    /**
     * 获取用户真实IP地址，不使用request.getRemoteAddr()的原因是有可能用户使用了代理软件方式避免真实IP地址,
     * 可是，如果通过了多级反向代理的话，X-Forwarded-For的值并不止一个，而是一串IP值
     *
     * @return ip
     */
    public static String getIpAddr(HttpServletRequest request) {
        String ip = request.getHeader("x-forwarded-for");
        // 多次反向代理后会有多个ip值，第一个ip才是真实ip
        if (!(ip == null || ip.length() == 0 || UNKNOWN.equalsIgnoreCase(ip))) {
            ip = convertIfContain(ip);
        }
        if (ip == null || ip.length() == 0 || UNKNOWN.equalsIgnoreCase(ip)) {
            ip = request.getHeader("Proxy-Client-IP");
        }
        if (ip == null || ip.length() == 0 || UNKNOWN.equalsIgnoreCase(ip)) {
            ip = request.getHeader("WL-Proxy-Client-IP");
        }
        if (ip == null || ip.length() == 0 || UNKNOWN.equalsIgnoreCase(ip)) {
            ip = request.getHeader("HTTP_CLIENT_IP");
        }
        if (ip == null || ip.length() == 0 || UNKNOWN.equalsIgnoreCase(ip)) {
            ip = request.getHeader("HTTP_X_FORWARDED_FOR");
        }
        if (ip == null || ip.length() == 0 || UNKNOWN.equalsIgnoreCase(ip)) {
            ip = request.getHeader("X-Real-IP");
        }
        if (ip == null || ip.length() == 0 || UNKNOWN.equalsIgnoreCase(ip)) {
            ip = request.getRemoteAddr();
        }
        return ip;
    }

    private static String convertIfContain(String ip) {
        if (ip.contains(SEP)) {
            return ip.split(SEP)[0];
        }
        return null;
    }

    private RequestIpUtils() {
    }
}